1. Field of the Invention
The present invention relates to a recording method, a reproduction method, a recording apparatus, and a reproduction apparatus for recording data to or reproducing data from a write once type information recording medium, and a recording medium. More specifically, the present invention relates to a recording method, a reproduction method, a recording apparatus, and a reproduction apparatus for recording or reproducing management information which represents a recording state of a recording medium, and a recording medium having management information recorded thereon.
2. Description of the Related Art
Recently, information recording media represented by hard discs and optical discs have been increased in their recording density and capacity. As the recording density and the recording capacity increase, it becomes more important to guarantee the reliability of the discs.
As write once type optical discs, CD-R discs have been remarkably widespread. CD-R discs are well known for of their low prices and wide usability of being reproducible by most CD players, and are widely used for creating original user CDs.
DVDs, too, are becoming being widespread in the U.S. and Japan. DVDs are widely used for recording high quality moving pictures due to their feature of a large capacity.
DVD-R discs, which are write once type optical discs in conformity to the DVD standards, are expected to be widespread in the future.
FIG. 1 schematically shows a recording face of a DVD-R disc. The recording face has a substantially continuous groove 101 formed therein. The groove 101 is wobbled at a certain cycle, and is cut at predetermined positions. The cycle of wobbles is referred to as a “wobble cycle”, and the positions at which the groove 101 is cut is referred to as an “LPP (land pre-pit)”.
Data is recorded on a DVD-R disc by emitting laser light in a pulse like manner while the laser light is caused to track a land 102 interposed between two adjacent grooves 101 so as to form pits (not shown) on the land 102.
FIG. 2 shows a waveform of a tracking error signal obtained by light reflected by the DVD-R disc. The waveform of the tracking error signal is obtained by adding pulses at the LPPs to the sine wave having a wobble cycle. The wobble and the LPP can both be used as a synchronous signal pre-recorded by cutting on the DVD-R disc.
By using the pre-recorded synchronous signals, the laser light can be positioned even on a new DVD-R disc having no pits formed on the land. On the DVD-R disc, data is recorded in the form of pits. The data is recorded in synchronization with the synchronous signals pre-recorded on the DVD-R disc (i.e., in positional alignment with the wobbles and LPPs). Herein, such synchronization will be referred to as “pre-pit synchronization”.
FIG. 3 shows the relationship between information on cutting of a DVD-R disc and information to be recorded. A waveform 301 represents a tracking error signal, which has a wobble cycle. As shown in FIG. 3, 8 wobble cycles equals to one frame cycle. An LPP is positioned at each of the leading three wobble cycles of each frame cycle.
3-bit information can be represented for each frame cycle based on whether the LPP exists or not. The 3-bit information is referred to as “pre-pit information”. Regarding the meaning represented by the pre-pit information, modulation rules are defined as follows, for example. In the case where the presence of an LPP is represented by “1b” and the absence of an LPP is represented by “0b”, “111b” represents a break in the pre-pit information, “100b” represents information 0, and “101b” represents information 1. The pre-pit information includes, for example, information on positions on the disc.
Data to be recorded on the DVD-R disc starts with the leading frame of pre-pit information. 26 frames form one sector, and 16 sectors form one ECC block. One sector includes 2048 byte user data, a synchronization mark (for example, SY0, SY1 and SY5 in FIG. 3), a sector ID used for identifying each sector, an IED as an error correction code for the sector ID, and an ECC as an error correction code for the user data.
Each sector includes an error correction code which has been calculated in units of ECC blocks. Accordingly, recording to and reproduction from a DVD-R disc need to be performed in units of ECC blocks.
A write once type recording medium does not allow information once recorded from being erased. Due to this feature, new information is additionally recorded at other portions of the DVD-R disc instead of overwriting information once recorded. Therefore, a write once type recording medium has different management information from that of a rewritable recording medium. In a CD-R disc, data is managed in units of tracks and sessions. A track corresponds to, for example, a tune in the case of a music CD. A collection of tracks reproducible by a player is referred to as a session. Similarly in the case of a DVD-R disc, there are concepts of RZone and border. RZone corresponds to the track, and border corresponds to the session.
FIG. 4 schematically shows additional recording of information on a DVD-R disc. A recording area of a DVD-R disc is divided into an R information area 401 (R-info.), a lead-in area 402 (Lead-In), a data area 403 (Data Area), and a lead-out area 404 (Lead-Out) which are located from the innermost part to the outermost part of the DVD-R disc.
R-info. is specific to the DVD-R disc and includes a power calibration area (PCA) 411 and a recording management area (RMA) 412.
In the data area 403, user data is recorded. The lead-in area 402 and the lead-out area 404 are buffer areas provided in preparation of overruns of the recording/reproduction head when the recording/reproduction head accesses the data area 403. A border-in area and a border-out area described below also act as a buffer area. In the lead-in area 402, an area bordering the data area 403 is referred to as an “extra-border zone” 421. The extra-border zone plays substantially the same role as that of the border-in area.
In the data area 403, an area which is not explicitly reserved is referred to as an invisible RZone. In anew DVD-R disc, the entire data area 403 is an invisible RZone.
When an area for storing a content to be recorded (for example, one music tune, one drama of video, or one file of computer data) is reserved, an RZone is formed at the start of the invisible RZone. Data of the content can be recorded sequentially from the start of the RZone. When the size of the content is not known, the data of the content can be recorded sequentially from the start of the invisible RZone.
In order to place a DVD-R disc having contents recorded thereon into a state reproducible by a DVD player, an area to be reproduced and buffer areas interposing the area to be reproduced need to be recognizable as recorded areas. The reason is because DVD players generally cannot read the information on cutting on DVD-R discs and reproduce recorded data using only the pit information recorded in the land as a clue. For the purpose of making the area to be reproduced and the buffer areas identifiable as recorded areas, when the reserved RZone still includes an unrecorded area, such an unrecorded area is filled with 0 padding data so that the unrecorded area is recognizable as a recorded area (this procedure is referred to as a “closing of RZone”). In addition, predetermined data is recorded in the extra-border zone (or the border-in area) and the border-out area interposing the unrecorded area (this procedure is referred to as a “closing of border”).
An area in contact with and radially farther than the border-out area is kept empty as a border-in area for the user data to be recorded next. Accordingly, the invisible RZone starts with an area in contact with and radially farther than the empty border-in area. The border-out area and the border-in area adjacent to each other are collectively referred to as a “border zone”.
For further recording additional content on the DVD-R disc, the data of the content is recorded from the start of the invisible RZone. When all the contents are recorded on the DVD-R disc, the lead-out area is made recognizable identifiable as a recorded area in addition to performing the closing of border (this procedure is referred to as “finalization”). Once a DVD-R disc is finalized, no more data can be added to the DVD-R disc.
The recording management area (RMA) 412 manages a change in the recording state in the lead-in area and the lead-out area. The RMA 412 includes an RMA lead-in area representing the start of the RMA 412 and recording management data (RMD). The RMA 412 is immediately preceded by a linking loss area (LLA), which acts as a runway used for establishing PLL synchronization or frame synchronization required for data reproduction.
In a DVD-R disc, error correction codes are calculated in units of ECC blocks. Therefore, the size of each RMD is an ECC block. At, for example, the time immediately before the DVD-R disc is discharged from a recording apparatus, the position of each border zone and the position of each RZone at that point, for example, are recorded as RMD on the DVD-R disc. When the recording management area (RMA) 412 is updated for the first time, predetermined data is recorded in the LLA, RMA lead-in area, and an RMD #1 area. When the recording management area (RMA) 412 is updated the next time, predetermined data is recorded in an RMD #2 area.
Thus, RMD represents the recording state of the DVD-R disc at each point during recording of user data in the data area 403.
The RMD #1 area, the RMD #2 area, . . . RMD #700 area are included in the RMA 421. The RMD #1 area through the RMD #700 area are a plurality of blocks, each of which is used for recording management information. In the following description, The RMD #1 area, the RMD #2 area, . . . the RMD #700 area will sometimes be simply referred to as “RMD#1, RMD#2, . . . RMD#700”. “RMD” represents data (management information) recorded in these blocks. The management information is sequentially recorded from the start of a leading portion of the RMA 421. Therefore, among the blocks having data recorded therein which are included in the RMA 421, the latest information is recorded in the rearmost block having data recorded therein.
FIGS. 5A and 5B show a linking operation of additionally recording data after a recorded area. In FIG. 5A, recorded data is represented by hatching, and data to be additionally recorded is not provided with hatching. For stopping the recording of old data (hatched in FIG. 5A), the recording is stopped after recording 16-byte data including the synchronization mark SY0 and the sector ID in a sector (referred to as a “connecting sector”) following the final sector in the final ECC block. Recording of new data (non-hatched in FIG. 5A) is started with recording the 17th byte data at the position of 16 bytes±1 byte counted from the synchronization mark of the connecting sector.
FIG. 5B shows the state of the connection sector after the linking operation. Additionally recorded data is coupled to the old data in the leading frame of the connecting sector with a shift within ±1 byte. A shift of even one bit causes erroneous demodulation of data from the connecting position to the next synchronization mark (SY5). However, such erroneously demodulated data is finally recovered by error correction.
The RMD recorded in the RMA is, as described above, important management information representing the recording state of the DVD-R disc. Unless the latest RMD can be recorded in the RMA correctly (namely, recorded in a state in which the RMD is reproducible with certainty), no more data can be additionally recorded to the DVD-R disc. When this occurs, the characteristic large capacity of the DVD-R disc cannot be utilized. As the memory capacity of the disc is larger, the loss is larger.
For example, when the quality of wobble signals of data is poor and thus the locked state of the wobble PLL is unstable, the positions of the wobbles and LPPs pre-formed in the DVD-R disc may be undesirably shifted significantly from the position of the RMD recorded on the DVD-R disc. In such a case, the RMD which is recorded after that data in positional alignment with the wobbles and LPPs may become unreadable.